Polycyclic Aromatic Hydrocarbons in PM2.5 and PM2.5–10 in Urumqi, China: Temporal Variations, Health Risk, and Sources

PM2.5 and PM2.5–10 samples were simultaneously collected in Urumqi from January to December 2011, and 14 priority polycyclic aromatic hydrocarbons (PAHs) were determined. The mean concentrations of total PAHs in PM2.5 and PM2.5–10 were 20.90~844.22 ng m−3 and 19.65~176.5 ng m−3 respectively, with the highest in winter and the lowest in summer. Above 80% of PAHs were enriched in PM2.5, which showed remarkable seasonal variations compared to coarse particles. High molecular weight (HMW) PAHs were predominant in PM2.5 (46.61~85.13%), whereas the proportions of lower molecular weight (LMW) and HMW PAHs in PM2.5–10 showed a decreasing and an increasing trend, respectively, from spring to winter. The estimated concentrations of benzo[a]pyrene equivalent carcinogenic potency (BaPeq) in PM2.5 (10.49~84.52 ng m−3) were higher than that of in PM2.5–10 (1.15~13.33 ng m−3) except in summer. The estimated value of inhalation cancer risk in PM2.5 and PM2.5–10 were 1.63 × 10−4~7.35 × 10−3 and 9.94 × 10−5~1.16 × 10−3, respectively, far exceeding the health-based guideline level of 10−4. Diagnostic ratios and positive matrix factorization results demonstrated that PAHs in PM2.5 and PM2.5–10 were from similar sources, such as coal combustion, biomass burning, coking, and petroleum combustion, respectively. Coal combustion was the most important source for PAHs both in PM2.5 and PM2.5–10, accounting for 54.20% and 50.29%, respectively

Humidity and PM2.5 composition determine atmospheric light extinction in the arid region of northwest China

Atmospheric visibility can directly reflect the air quality. In this study, we measured watersoluble ions (WSIs), organic and element carbon (OC and EC) in PM2.5 from September 2017 to August 2018 in Urumqi, NW China. The results show that SO42-, NO3- and NH4+ were the major WSIs, together accounting for 7.32%-84.12% of PM2.5 mass. Total carbon (TC=OC+EC) accounted for 12.12% of PM2.5 mass on average. And OC/EC > 2 indicated the formation of secondary organic carbon (SOC). The levels of SO42-, NO3- and NH4+ in low visibility days were much higher than those in high visibility days. Relative humidity (RH) played a key role in affecting visibility. The extinction coefficient (b(exi)) that estimated via Koschmieder formula with visibility was the highest in winter (1441.05 +/- 739.95 Mm(-1)), and the lowest in summer (128.58 +/- 58.00 Mm(-1)). The beat that estimated via IMPROVE formula with PM2.5 chemical component was mainly contributed by (NH4)(2)SO4 and NH4NO3. The beat values calculated by both approaches presented a good correlation with each other (R-2 = 0.87). Multiple linear regression (MLR) method was further employed to reconstruct the empirical regression model of visibility as a function of PM2.5 chemical components, NO2 and RH. The results of source apportionment by Positive Matrix Factorization (PMF) model showed that residential coal combustion and vehicle emissions were the major sources of beat. (C) 2020 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V

Polycyclic Aromatic Hydrocarbons in PM2.5 and PM2.5-10 in Urumqi, China: Temporal Variations, Health Risk, and Sources

PM2.5 and PM2.5-10 samples were simultaneously collected in Urumqi from January to December 2011, and 14 priority polycyclic aromatic hydrocarbons (PAHs) were determined. The mean concentrations of total PAHs in PM2.5 and PM2.5-10 were 20.90844.22 ng m(-3) and 19.65176.5 ng m(-3) respectively, with the highest in winter and the lowest in summer. Above 80% of PAHs were enriched in PM2.5, which showed remarkable seasonal variations compared to coarse particles. High molecular weight (HMW) PAHs were predominant in PM2.5 (46.6185.13%), whereas the proportions of lower molecular weight (LMW) and HMW PAHs in PM2.5-10 showed a decreasing and an increasing trend, respectively, from spring to winter. The estimated concentrations of benzo[a]pyrene equivalent carcinogenic potency (BaPeq) in PM2.5 (10.4984.52 ng m(-3)) were higher than that of in PM2.5-10 (1.1513.33 ng m(-3)) except in summer. The estimated value of inhalation cancer risk in PM2.5 and PM2.5-10 were 1.63 x 10(-4)7.35 x 10(-3) and 9.94 x 10(-5)1.16 x 10(-3), respectively, far exceeding the health-based guideline level of 10(-4). Diagnostic ratios and positive matrix factorization results demonstrated that PAHs in PM2.5 and PM2.5-10 were from similar sources, such as coal combustion, biomass burning, coking, and petroleum combustion, respectively. Coal combustion was the most important source for PAHs both in PM2.5 and PM2.5-10, accounting for 54.20% and 50.29%, respectively

Temporal distribution and source apportionment of PM2.5 chemical composition in Xinjiang, NW-China

Daily fine particulate matter samples were collected in Dushanzi district within four months from September 2015 to August 2016 and represent the four seasons. The samples were determined for major chemical components in PM2.5, including elements, water-soluble ions (WSIs) and the organic/elemental carbon (OC/EC). The results indicated that the annual mean PM2.5 concentration was 62.85 +/- 43.5 mu g m(-3) in the Dushanzi district, with the highest seasonal average in winter (95.47 +/- 61.7 mu g m(-3)) and the lowest in summer (33.22 +/- 17.7 mu g m(-3)). The crustal elements were the most abundant elements and accounted for 96.51% of the total analyzed elements. Carcinogenic metals, such as Cr, Pb, As and Cd, originated from human activity, especially during winter. The highest total WSI concentration was 68.99 mu g m(-3) in winter, followed by autumn (16.32 mu g m(-3)), spring (10.23 mu g m(-3)) and summer (7.06 mu g m(-3)). SO42-, NO3- and NH4+ were the most abundant WSIs in Dushanzi. Ion balance calculations showed that PM2.5 in winter was acidic; in autumn and spring alkaline; and in summer nearly neutral. Total carbonaceous aerosol (TCA) accounted for 34% of the PM2.5. The chemical mass closure (CMC) indicated that minerals and WSIs were the major fraction, accounting for 33.58% and 23.17% of PM2.5 mass concentration, respectively. Dushanzi was controlled by four major air masses, and the relative contributions of these air masses differ by season. Positive matrix factorization (PMF) analysis identified six sources including vehicle emission, biomass burning, coal combustion, industrial pollution, secondary aerosols and soil dust, with annual mean contributions of 9.43%, 10.86%, 18.45%, 12.15%, 18.26% and 30.85%, respectively. Moreover, the relative contributions of these identified sources varied significantly with the changing seasons

Concentration characteristics, source apportionment, and oxidative damage of PM2.5-bound PAHs in petrochemical region in Xinjiang, NW China

Polycyclic aromatic hydrocarbons (PAHs) are of considerable concern due to their potential as human carcinogens. Thus, determining the characteristics, potential source, and examining the oxidative capacity of PAHs to protect human health is essential. This study investigated the PM2.5-bound PAHs at Dushanzi, a large petrochemical region in Xinjiang as well as northwest China. A total of 33 PM2.5 samples with 13 PAHs, together with molecular tracers (levoglucosan, and element carbon), were analyzed during the non-heating and heating periods. The results showed that the PM2.5 concentrations were 70.22 +/- 22.30 and 95.47 +/- 61.73 mu g/m(3), while that of total PAHs were 4.07 +/- 2.03 and 60.33 +/- 30.80 ng/m(3) in sampling period, respectively. The fluoranthene, pyrene, chrysene, benzo[b]fluoranthene, and benzo[k]fluoranthene were the most abundant (top five) PAHs, accounting for 71.74 and 72.80% of total PAH mass during non-heating and heating periods. The BaP equivalent (BaPeq) concentration exceeded 1 ng/m(3) as recommended by National Ambient Air Quality Standards during heating period. The diagnostic ratios and positive matrix factorization indicated that oil industry, biomass burning, coal combustion, and vehicle emissions are the primary sources. The coal combustion remarkably increased during heating period. The plasmid scission assay (PSA) results showed that higher DNA damage rate was observed during heating period. PAHs in PM2.5 such as Chr, BaP, and IcdP were found to have significantly positive correlations with the plasmid DNA damage rates. Additionally, the relationship among BaPeq and DNA damage rate suggested that synergistic reaction may modify the toxicity of PAHs

Chemical Characteristics and Source Apportionment of PM2.5 during Winter in the Southern Part of Urumqi, China

Urumqi, the administrative center of Xinjiang, suffers from severe atmospheric aerosol pollution; however, no study has comprehensively analyzed the local constituents and sources of fine particulate matter (PM2.5). The characteristics of PM2.5 in Urumqi were observed the first winter (2012-2013) after natural gas replaced coal as an energy source. Enrichment factors, backward trajectories, the potential source contribution function (PSCF) model, and positive matrix factorization (PMF) were used to identify the source area and categories. The results showed a mean concentration of 197.40 mu g m(-3) for the PM2.5, which significantly decreased after the conversion from coal to natural gas. Although the concentration of NO3- increased post-conversion, the SO42- and Cl- decreased by 42.54% and 32.93%, respectively. The water-soluble ions (WSIs) mainly consisted of NH4HSO4, CaSO4, MgSO4, Ca(NO3)(2), Mg(NO3)(2), and KCl. Elements such as Pb, Cr, and As decreased following the fuel switch. The organic carbon and elemental carbon were strongly correlated, and the mean concentration of the secondary organic carbon was 18.90 mu g m(-3). Pyr, Chr, BbF, BkF, IcdP, and BghiP were the most prevalent individual polycyclic aromatic hydrocarbons, and BaP exceeded health-based guidelines. The results from trajectory clustering and PSCF modeling suggested that emissions from both the city and its surroundings, as well as the valley-and-basin topography, may be responsible for the heavy PM2.5 pollution in southern Urumqi. PMF identified five primary sources: secondary formation, biomass and waste burning, vehicle emissions, crustal minerals, and industrial pollution and coal combustion